Routes of formation for porous silicon

Abstract

Porous silicon has been fabricated by both "top-down" techniques from solid silicon and "bottom-up" routes from silicon atoms and silicon-based molecules. Over the last 50 years, electrochemical etching has been the most investigated approach for chip-based applications and has been utilized to create highly directional mesoporosity and macroporosity. Chemical conversion of porous or solid silica is now receiving increasing attention for applications that require inexpensive mesoporous silicon in powder form. Very few techniques are currently available for creating wholly microporous silicon with pore size below 2 nm. This review summarizes, from a chronological perspective, how more than 30 fabrication routes have now been developed to create different types of porous silicon.